The King

The King is the primary "antagonist" in Mabel. He has no credited voice actor, but one can assume his voice is a corrupted version of Becca De La Rosa's.

All Seasons
The King of the Underhill has been ruling for eons, his form shifting and changing with the above-world seasons. He cares little for anything or anyone save for Mabel Martin; his most relevant characterization comes from his caging of Luna Thorne after she betrays her promise to him as his consort. He watches Sally Martin die and allows Mabel and Anna Limón to best him in a challenge, losing his throne to Anna and disappearing. It has been confirmed he will return in season seven.